The AK that was (or wasn't)

[Jim Ferer]

Pip!Squeak, discussing the "force" of spells: " True, but in that
case, it's the first time we've seen Expelliamus. The apparent problem
with Expelliamus is *not* hitting the opposing wizard with the force
of several tons of bricks, instead learning to control the force of
the spell so that you only remove the wand. Expelliamus throws people
around on several occasions, not just the once."

Yes, and here's the first time we saw it:

"Both of them swung their wands above their heads and pointed them at
their opponent; Snape cried: "Expelliarmus!" There was a dazzling
flash of scarlet light and Lockhart was blasted off his feet: He flew
backward off the stage, smashed into the wall, and slid down it to
sprawl on the floor."

Who was that who blew Lockhart off his feet? Lucky for Gilderoy they
weren't on the Astronomy Tower.  We have Bella's example as well.

We see it other times, not just by Snape, that spells can have a
physical force beside their primary effect. It seems to happen most
often when the caster's adrenaline is up; not hard to believe. Snape,
malicious so-and-so that he is, would no doubt put a little extra
oomph into every hurtful spell he cast. Voldemort probably wouldn't;
he didn't care two pins for Frank Bryce, he just wanted him out of the
way.  Same for Wormtongue - er, Wormtail - and Cedric, "the spare."

Jim Ferer